1. Field of the Invention
The present invention relates to car audio equipment and, in particular, to car audio equipment having cabin loudspeakers attached to predetermined positions in a vehicle cabin, so as to enable sound output of the audio equipment through the cabin loudspeakers.
2. Description of Related Art
Automobiles are equipped with audio equipment so that a driver and one or more passengers can enjoy music and so forth during driving. The audio equipment comprises a radio tuner, a tape player, a CD player and so forth, obtains therefrom sound signals as sources (sound sources), and processes the sound signals to be output from loudspeakers. The loudspeakers are typically embedded in car doors, so as to allow the loudspeakers to reproduce sound.
A car navigation device equipped in the car is designed to use ATT signals so as to output a voice of navigation guidance. A voice output unit of the navigation device is provided in common with a sound output unit of the car audio equipment, so that the voice of the navigation guidance of the car navigation device is output by attenuating or muting audio outputs of the car audio equipment, which are signals of music and so forth, and by overlaying or inserting thereto the navigation guidance voice.
The navigation guidance voice is useful for the driver, but maybe substantially useless for a passenger, and may make them feel unpleasant because the music output reproduced by the CD player and so forth is interrupted. Also, an output unit of the radiotuner is provided in common with the loudspeakers of the audio equipment, so that the driver who wants to listen to traffic information, such as traffic jam information on the radio receiver, has to interrupt music that the passenger is enjoying and to exchange the audio source from the CD player to the radio tuner. Also, this situation makes the passenger feel unpleasant not only because the music he/she is listening is interrupted, but also because he/she is forced to listen to the unnecessary traffic jam information.
During midnight driving or the like, the driver who wants to enjoy music cannot enjoy it with an appropriate volume if the passenger falls a sleep. In a configuration having the car audio equipment linked with a mobile phone or a car telephone set, the loudspeakers of the audio equipment reproduce the voice of the opposite party when a phone call is received. This situation also raises nonconformities not only in that the music under reproduction is interrupted, but also in that the passenger may possibly hear the conversation. For the case where the mobile phone or the car telephone set is linked with the audio equipment, reproduction of the received voice through the audio loudspeakers is allowed only when the driver can drive alone while reproducing it.
Japanese Patent Application Publication (KOKAI) No. Hei 2-305157 discloses a car telephone control device comprising a handset holder having handset detection means detecting the presence or absence of a handset of a car telephone set, and also having a transmission loudspeaker and a transmission microphone respectively in correspondence with a mouthpiece and an earpiece of the handset; seating detection means detecting the presence or absence of a seated person; a pair of side-headrests disposed on the left and right sides of a headrest on a top end of a seat back so as to be freely slidable forward and backward, and so as to be swung respectively to a setback position, a riding position and a speaking position corresponding to the presence or absence of the seated person, and also to the presence or absence of the handset on the handset holder; pillow loudspeakers built in the side-headrest so as to output selectively sound from car components and voice from a transmission microphone; a speaking microphone disposed in a swingable manner on the side of one side-headrest and being communicated with the transmission loudspeaker of the handset holder, and it is swung from a housing position not interfering with the driving operation or getting on and off of the seated person to a speaking position where the seated person can speak, based on the detection of the handset by a handset detection unit; a headrest motor which swings the side-headrest; a speaking microphone motor which swings the speaking microphone; and a central processing unit which processes input information according to a predetermined program, and controls operations of the headrest motor and the speaking microphone motor and switching of output sound from the pillow loudspeakers; wherein the output sound from the pillow loudspeakers is switched to voice from the car telephone upon placement of the handset on the handset holder, and at the same time the side-headrest and speaking microphone are swung to the speaking position, so as to set up a speaking environment.
The above-described configuration, however, inevitably interrupts the reproduction of sound of the car audio equipment during use of the car telephone and, therefore, cannot solve the problem that the passenger cannot enjoy music. The equipment is also disadvantageous in that it provides no solving means at all for harmonization of the voice output of navigation guidance by the car navigation device and the sound output from the audio equipment, because the equipment is not communicated with the car navigation device.    [Patent Document 1] Japanese Patent Application Publication (KOKAI) No. Hei 2-305157    [Patent Document 2] Japanese Patent Application Publication (KOKAI) No. 2000-5385    [Patent Document 3] Published Japanese Translation of PCT International Publication for Patent Application (KOHYO) No. 11-501479; and    [Patent Document 4] Japanese Patent Publication No. 2554224.